1. Field
Apparatuses consistent with exemplary embodiments relate to optical structures and apparatuses including the same, and more particularly, to electromagnetic wave focusing devices and optical apparatuses including the same.
2. Description of the Related Art
As nano device technology has developed, various options for manufacturing thin film type/ultra-compact type optical elements and optical devices have been developed. Also, interest has increased in technologies that promise a high resolving power beyond the resolution limit of existing optical systems. High resolving power technology may have a ripple effect on many fields requiring high-resolution imaging, such as biotechnology and analysis technology. In particular, a non-fluorescent type “true” super-resolution technology is desired, as compared to a “functional” super-resolution technology using fluorescent materials.
In the case of a Faraon type metasurface, lens performance is implemented by arranging numerous amorphous silicon (a-Si) nanoposts on a substrate. However, since absorption coefficients of nanoposts are large in the visible light region, it is difficult to use nanoposts in the visible light region. Also, since nanoposts having smaller sizes are necessary for use in wavelength regions, the processing difficulty is increased.
In the case of a Pendry superlens, an image is formed in a point area by using a metamaterial having a negative (−) refractive index regardless of a diffraction limit. However, a complicated and difficult process is needed for manufacturing a Pendry superlens. Also, it is almost impossible to manufacture a metamaterial having a negative refractive index in various visible light wavelength regions, and there is a fundamental limitation such as light loss by metal.
In the case of near-field scanning optical microscopy (NSOM), although resolution may be increased by using a near field of a metal tip, it is required that a distance between the metal tip and a sample is shorter than a wavelength. Accordingly, there is the difficulty that a user is required to have high-level proficient technique, expensive equipment is necessary, and coupling efficiency is low.
In order for common users/customers to use products with high resolving power/super-resolution imaging technology, various requirements, such as, mass producibility, price competitiveness, miniaturization, user-friendly user interface (UI), etc., may be desired.